As documents describing handover techniques, there are Patent Document 1 and Patent Document 2.
Patent Document 1 discloses: “a mobile communication system comprises a plurality of base stations, a plurality of wireless zones covered by the base stations, and mobile stations movable in the wireless zones, and uses one of a plurality of channels to transceive voice and data between one of the base stations and one of the mobile stations, the wireless zones continue from one to the next to form an extended wireless zone, the first base station BS11 of the base stations BS11 to BS51 notifies frequency information item(s) f11 to f51 and position information item(s) of the remaining one or more base stations, and the mobile station has a GPS receiver, and includes means for receiving the frequency information and the position information of the one or more base stations notified from the first base station BS11, detecting switching locations of wireless zones based on the data of the GPS receiver and the received position information, and triggered by the detection, switching the frequency to the frequency of the succeeding base station BS12.” (extracted from the Abstract)
Patent Document 2 discloses, as an example of dedicated short range communications (DSRC) technique in highway traffic communication systems: “in a travelling support system including a plurality of wireless base station equipment, which are arranged on the side of a road, and on-board wireless communication equipment, the wireless base station equipment transmits an inquiry about a traveling state of a vehicle located within a predetermined range of a road to the on-board wireless communication equipment, and responsive to the inquiry, the on-board wireless communication equipment transmits a response including vehicle identification information and traveling state information indicating the traveling state of the vehicle to the wireless base station equipment. Upon receipt of the response, the wireless base station equipment extracts the vehicle identification information and the traveling state information from the response, stores them in a storage device, analyzes the traveling state information stored in association with the vehicle identification information in the storage device, determines the traveling state of the vehicle, and to the on-board wireless communication equipment, transmits necessary information according to the traveling state.” (extracted from the Abstract)